N-acylaminophenylcyclopropanes in reaction with nitrous acid generated in situ

Reactive nitrogen species: Nitrosonium ions in organic synthesis

“…Oxidative addition of the nitrosonium ion to the cyclopropane unit yielded isoxazolines 26. [33] Sodium nitrite served as source for nitrosonium ions, since they were generated in situ under the acidic reaction conditions. However, undesired nitration, formation of benzoxazines, and formation of quinolines as by-products limited the synthetic applicability.…”

“…Recently, Tu's group reported the incorporation of nitrosonium tetrafluoroborate using silyl allyl ethers 32 (Scheme 11). [37] The developed reaction conditions allowed the synthesis of different polycyclic oximes (33) in good yields and short reacting times via a semipinacol rearrangement. According to the proposed mechanism, the nitrosonium cation reacts with the enolic double bond (32A), inducing the C-C bond migration of the cyclobutan moiety to form intermediate 32B.…”